The invention relates to a continuously working severing machine in the form of a horizontal bandsaw, cold circular saw, severing grinding machine or the like. Such machine is provided with a machine stand forming a workpiece table on which the workpiece rests, and clamping jaws, mounted on the table for clamping the workpiece in position. The machine further includes a machine head articulated pivotably in the feed direction of the tool or vertically displaceably guided on the machine stand and containing the rotating tool. The machine head is pivotable or mobile in the direction towards the workpiece with the aid of a feed device for tool feed motion and to generate the cutting pressure between tool and workpiece, dependent upon the workpiece material and cross section. The feed device is drivable, possibly at high speed, after completion of a working operation into the position for the beginning of the next working operation, the feed device, on the one hand, being supported by the machine stand and, on the other hand, acting upon the machine head.
In such known severing machines, the feed device for the machine head is constituted for example by a cylinder-piston unit acting on the machine head. In dependence upon the workpiece material and maximum workpiece cross section, the cylinder-piston unit is charged with hydraulic pressure so that the tool, as far as possible, exerts the optimum cutting force. Here, however, working conditions vary in the case of a workpiece cross section which as a rule varies in the working direction, which conditions can be compensated only with difficulty by controlling the pressure applied to the cylinder-piston unit. Here, however, large quantities of pressure oil must be pumped around through an adjustable pressure relief valve, which oil correspondingly heats up during working and again leads to falsification of the setting, in that this oil influences the regulating valves and their settings. Furthermore the power necessary for pumping around the pressure oil and the energy absorbed in the form of heating of the pressure oil are uselessly lost. As a whole such a known feed device cannot react in a highly sensitive manner to the conditions prevailing at each moment at the cutting position.
On the other hand mechanical feed devices are also known which work with electronically controlled stepping motors as feed motors, in which case by means of the electronic system attempts are made to satisfy the conditions predetermined by the workpiece in each case. Here again, specifically in the case of workpiece cross sections, which vary in the cutting direction, highly sensitive adaptation is possible only at considerable expense.